1. Field of the Invention
The present invention relates to a control valve controlling a flow rate of fluid such as gas or liquid.
2. Description of the Prior Art
A control valve the of normal close type shown in for example FIG. 6 has been known as a control valve for controlling a flow rate of fluid such as gas and liquid.
Referring to FIG. 6, reference numeral 31 designates a passage block and reference numeral 32 designates a flowing-in conduit formed in said passage block 31. Said flowing-in conduit 32 is closed by a partition wall 33 at an end portion thereof and a flowing-out conduit 34 is formed through said partition wall 33. Reference numeral 35 designates a valve chamber formed on the side portion in a radial direction of said flowing-in conduit 32 and said flowing-out conduit 34 while communicating with them and reference numeral 36 designates a valve seat formed on an end portion of the flowing-out conduit 34 with facing to said valve chamber 35.
Reference numeral 37 designates an inner cylinder made of a nonmagnetic material mounted on the passage block 31 at an end portion thereof. Reference numeral 38 designates a movable core made of a magnetic material, such as iron, slidably inserted into said inner cylinder 37 and said movable core 38 is inserted into the valve chamber 35 at an end portion thereof. Reference numeral 39 designates a valve body provided on an end face of the movable core 38 and reference numeral 40 designates a plate spring mounted on the movable core 38 at an end portion thereof and fixedly mounted on the passage block 31 at the other end thereof for supporting the movable core 38.
Reference numeral 41 designates a fixed core opposite to the movable core 38 and fixedly mounted on the inner cylinder 37 at a sliding gap 42. Also said fixed core 41 is made of a magnetic material. Reference numeral 43 designates a coil provided on an outer circumference of the inner cylinder 37 for magnetizing the fixed core 41 and reference numeral 44 designates an outer cylinder.
In this flow rate control valve, the flowing-in conduit 32 is supplied with a fluid such as gas. In order to flow said fluid from the flowing-in conduit 32 to the flowing-out conduit 34, a voltage is applied to said coil 43. Thereupon, the fixed coil 41 is magnetized to draw the movable core 38 against a force of said plate spring 40, whereby separating said valve body 39 from said valve seat 36 to open the valve seat 36, and thus the fluid flows into the flowing-out conduit 34 from the flowing-in conduit 32 through the valve chamber 35.
A flow rate of the fluid flowing in the above described manner is controlled by changing said voltage applied to the coil 43 to change a magnetic force of the fixed core 41, whereby changing a sliding quantity of the movable core 38 to change an interval between the valve seat 36 and the valve body 39.
In the above described conventional flow rate control valve, the valve chamber 35 and the inner cylinder 37 are positioned on the side portion of a flowing course of fluid, so that they provide a considerable dead space.
Moreover, when the fluid is flown from the flowing-in conduit 32 to the flowing-out conduit 34, an attraction of the flowing fluid acting upon the fluid flowing into the valve chamber 35 and the inner cylinder 37 is reduced on account of the above described construction, so that the fluid flows slowly and difficultly within the valve chamber 35 and the inner cylinder 37, whereby a problem occurs in that the displacement is slowed down or deteriorated.
For example, in the case where the flowing gas is a sample gas of which components are to be measured, a problem has further occurred in that an analytical accuracy is deteriorated because of a gas of which displacement is slowed down or made difficult.